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Tuesday, August 08, 2006

Consciousness by degrees? The Phenomenal and the Sorites

The Sorites is an ancient argument/paradox which derives an apparently absurd conclusion from seeminingly innocuous premises. One version goes like this:

1. A single grain of sand is not a heap.2. If a collection of n grains of sand is not a heap, a collection of n + 1 grains of sand is not a heap.3. A collection of one million grains of sand is not a heap.

(The argument works just as well in reverse, in which case we conclude that if a million grains of sand is a heap, and a heap cannot be turned into a non-heap by subtracting a single grain of sand, a single grain of sand counts as a heap)

This general argument, or something like it, can be used to generate similarly interesting conclusions about phenomenal consciousness.

When did "consciousness" appear in our evolutionary history? If we apply a variant of the sorites to consciousness, it seems there are two major possibilities. The first is that there is there a first conscious organism with phenomenal zombies (beings who lack phenomenal consciousness) for parents. Musn't there have been a large saltation if there was a first conscious organism with non-conscious parents? Can we really believe that between two creatures who are as similar as siblings, who share fifty percent of their variable DNA, that one fully enjoys phenomenal consciousness and the other not at all?The second option is that consciousness became manifest in parts and by degrees. But if consciousness comes in degress, we face another dilemma: are there any minimum requirements for possessing consciousness, or can we not stop until we say that everything is conscious? That seems very radical--but if we don't conclude this, musn't we posit a vast difference between the least phenomenal beings--the ones who possess the minimal degree of phenomenal consciousness-- and "the next ones down", who experience nothing? What physical difference, if any, would account for this? It seems we are caught between two implausible views: On the one hand, that there can be a vast difference in consciousness despite underlying physical continuity, and on the other, that everything down to the level of subatomic particles is conscious to some degree.

Clearly, "consciousness", whether that of a human or a chimp or a dog, is an *emergent* property; the question is, how much of the requisite entity (neurons or something more metaphysical) do we need to get (a) consciousness? For example, the phenomenon of sound is an emergent property: you can have a very thin gas with, say, 1000 molecules of air: that's not enough to transmit sound. So how many air molecules do you need to get sound? one million? or maybe a number in the vicinity of Avogadro's number, on the order of 10^23 air molecules? It would have to be established by experiment. Perhaps these experiments have been done. You could keep adding air molecules to a vacuum until sound would be transmissible. You could keep assembling neurons until you got some kind of consciousness, but even then, following Martin Heidegger, this proto-consciousness would have to "have some kind of world" for it to have a self-meaning, rather than just be a pointless assemblage. After all, even a housefly has a crude Identity and a World, as it belongs to a species established over millions of years of evolution and co-evolution. The simple housefly "carries its own idiomatic baggage", we could say.